WASHINGTON — More than 70 Jewish communal leaders, including the heads of the two largest synagogue unions, are pledging their support for aggressive American efforts to kick-start the peace process, and urging Israel to honor its commitment to freeze settlement construction.

They say such steps could improve the situation in Iraq.

The leaders outlined their views in a letter to National Security Adviser Condoleezza Rice, President Bush’s choice to be the next secretary of state. Organized by the Israel Policy Forum, the letter calls for the “empowerment of new moderate, pragmatic Palestinian leaders” and for the Bush administration to serve as a “credible, honest broker” in the Israeli-Palestinian arena.

The letter comes as the Bush administration is experiencing increased pressure from European and Arab leaders to press Israel into concessions aimed at helping the internal political standing of Palestinian moderates following the death of Yasser Arafat. Bush’s top European ally, British Prime Minister Tony Blair, recently made the point to President Bush at the White House, and Egypt’s foreign minister lectured Secretary of State Colin Powell on the issue at the opening of a 20-nation summit on Iraq this week in Egypt.

Many Jewish organizations have rejected any suggestion that American support for Israel has hampered the war on terrorism or American efforts in Iraq. In a sharp departure, however, the letter argues that American-led progress in the peace process would “encourage international support for America’s broad Middle East policy and diminish anti-Americanism in the Arab and Muslim world.” The letter states that “there are many challenging paths to achieving our country’s objectives in Baghdad and, we believe, one of them runs through Jerusalem.” It also suggests that “a successful democratic election” for president of the Palestinian Authority on January 9, 2005 “can only help in pointing the way to successful elections in Iraq later that month.”

The letter also urges increased American coordination with Arab and European nations “in order to enable the Palestinians to mount a genuine and concerted effort to prevent terrorist attacks against Israel,” but adds that “this is the right time for Israel to fulfill its commitments to stop settlement activity that it undertook to the [Bush administration] in April 2004.”

Among the letter’s most prominent signers were Rabbi Eric Yoffie, president of the Union for Reform Judaism, and Rabbi Jerome Epstein, executive vice president of The United Synagogue of Conservative Judaism. Their organizations represent more than 1,700 congregations combined, and an overwhelming majority of synagogue members in the United States. But each rabbi said he signed the letter as an individual, though Yoffie said he only did so after making sure that the letter reflects the positions of the Reform movement.

The top executives of most other influential Jewish groups did not sign on. The letter goes much further than the general endorsement of Israel’s Gaza disengagement plan offered up by most members of the Conference of Presidents of Major American Jewish organizations, generally seen as the community’s consensus voice on Israel.

Several of the signers said they realize that calling for an Israeli settlement freeze might be controversial. But, Yoffie said, “it’s clear to everybody, including the government of Israel, that if there is going to be a movement forward here, they are going to have to meet obligations that they have made.”

Both Israel and the United States took steps this week in line with the course outlined in the letter.

Powell met Tuesday in Egypt with Russian, European Union and United Nations representatives to discuss how the so-called diplomatic Quartet could help facilitate the post-Arafat transition in the territories. Powell and Russian Foreign Minister Sergei Lavrov said the Quartet would seek to provide the Palestinians with financial support for organizing elections. No specific amounts of money were mentioned.

The Quartet also urged Israel on Tuesday to ease restrictions on Palestinians before the election. The request came a day after Sharon promised Powell, who visited both Jerusalem and the West Bank city of Ramallah on Monday, that Israel would make every effort to ensure the success of the P.A. election.

Specifically, Sharon said, Israel would facilitate freedom of movement by opening transit points and withdrawing Israeli troops from the territories, but only on the condition that this does not harm Israel’s security. Sharon also said that East Jerusalem residents would be allowed to vote.

Meanwhile, Arafat’s Fatah faction tapped Mahmoud Abbas on Monday to be their candidate in the election.

The chance to replace Arafat with a more moderate Palestinian leadership and restart Israeli-Palestinian negotiations is what several Jewish communal leaders said prompted them to sign the letter to Rice.

The letter argues that Rice should make sure that the Bush administration works to empower moderate Palestinian leaders by improving the daily life of their people. The signers argue that U.S. policy should seek to encourage several steps, including “Israel’s easing of restriction of movement for Palestinians in the West Bank, allowing more Palestinians to work in Israel to support their families and releasing additional funds to the Palestinian Authority.”

The letter also urges Rice to help “Israel to reorient its plan to disengage unilaterally from Gaza and several settlements in the northern West Bank so that its originally unilateral character is shifted towards a more bilateral effort.”

While Jewish organizations active in Washington generally have voiced support for the current level of American participation in the peace process, they are not opposing administration efforts to convince Congress to authorize additional funding for the Palestinians in advance of the election.

Some hawkish groups, most prominently the Zionist Organization of America, oppose any American support for the Palestinian Authority and its leaders, reject President Bush’s oft-stated goal of creating a Palestinian state in West Bank and Gaza, and oppose any freeze on Jewish settlements.

The ZOA has issued statements this week calling on Congress to oppose financial aid to the Palestinians, condemning the administration for allegedly pushing Israel to “negotiate under fire,” to dismantle roadblocks in the West Bank and to make other concessions to the transitional Palestinian leadership of Abbas. The administration, said ZOA National President Morton Klein, is making “a tragic mistake” by embracing a man who is “Arafat in a suit.”

Organizers and signers of the letter contend that Klein speaks for the minority in the Jewish community. “This is a signal to Dr. Rice that she should pay attention to those who are prepared to support the president and the prime minister rather than those who want to drag this process down,” said Seymour Reich, a former chairman of the Presidents Conference, who played a lead role in organizing the letter.

Reich said that the letter also signals to the Palestinians that “there are Jewish voices in the U.S. that are prepared to back them when they [combat] terrorism and are ready to meet the Israelis on the road to negotiations.”

Marvin Lender, who organized the letter along with Reich and serves as chairman of the Israel Policy Forum’s executive committee, said: “Our intention is to encourage the administration to see through what the president and his aides — as well as Sharon — have already articulated, and to let the president know that he has the support of the Jewish community.”